Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session Q16: Engineered Soft Materials: New Approaches, Mechanisms and Structures II |
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Sponsoring Units: DSOFT Chair: Greg Van Anders, Queen's University; Laura Rossi, Delft University of Technology Room: Room 208 |
Wednesday, March 8, 2023 3:00PM - 3:12PM |
Q16.00001: Force Manipulation Across a Textile Metamaterial David Farrell, Connor M McCann, Antonio Elia Forte, Reza Sourki, Conor J Walsh, Katia Bertoldi The design of functional apparel currently requires a human intuition-based design approach to manipulate forces around the body. This design process often requires tedious trial and error, by combining regions of stretchable and inextensible material for comfort and to react tensile loads. However, this process typically leads to form fitting textiles that are difficult to don and doff. To solve this problem, we develop strategies to identify periodic textile metamaterials capable of manipulating internal forces directly. Using this inverse design tool, we can generate unique textile structures that are tight fitting to the body but relax during donning/doffing. Furthermore, we show that this framework can be applied to manipulate internal forces in a variety of ways, allowing us to realize and design a new generation of functional apparel textiles. |
Wednesday, March 8, 2023 3:12PM - 3:24PM |
Q16.00002: Diffusiophoresis: size segregation during drying of mixed-sized colloidal suspension confined between a thin gap Zhiyu Jiang, Jean Baptiste Salmon, H Daniel Ou-Yang Particle size-segregation during drying of mixed-sized colloidal suspension has been attributed to diffusiophoresis – migration of large particles in the concentration gradient of the small particles - however, individual particle migrations could also be due to convection or sedimentation unless conditions causing these effects can be ruled out and direct observation of particle migration can be made. To minimize the effects due to sedimentation and convection, experiments are made by 1) matching the particle-solvent mass density is made by using H2O/D2O mixtures as solvents for colloidal polystyrene particles and 2) controlling the thickness of the gap in which the drying takes place. Time-lapse fluorescence confocal microscopy is used to observe motions of both the large and small particles. Upon drying, a concentration gradient of the majority small fluorescent particles and the motion of the different color-labeled large tracer particles are measured. Relative motions of the large, tracer particles in the concentration gradient of the small particles are clearly observed. Drift speed of large particles as a function of the concentration gradient of the small particles for colloidal mixtures with different salt concentration is measured. Diffusiophoresis mobility, - the ratio of the drift velocity and the concentration gradient - decreases with increasing concentration gradient, and at a fixed gradient, also decreases with the salt concentration. The experimental results are compared against existing theories, computer simulations, and experiments by others. |
Wednesday, March 8, 2023 3:24PM - 3:36PM |
Q16.00003: Engineering Light Transport in Disordered Soft Materials Jennifer A McGuire, Anna B Stephenson, Ming Xiao, Victoria Hwang, Vinothan N Manoharan The optical properties of materials for applications such as structural color, UV filtering, and solar cells depend on a combination of absorption, multiple scattering, and constructive interference. The interplay between these effects can lead to unusual light transport properties such as enhancement of absorption. However, the physics underlying light transport in disordered materials with moderate multiple scattering and absorption is not well understood, making it difficult to engineer materials with prescribed optical properties. We use a Monte Carlo simulation to model the transport of light through disordered soft materials with embedded absorber. By investigating a variety of model systems, we develop a fundamental understanding of the effects of absorber placement on the optical properties of the material. We compare these simulations to preliminary experimental results to support our findings. |
Wednesday, March 8, 2023 3:36PM - 3:48PM |
Q16.00004: Particulated granular metamaterials with tunable elastic moduli Nidhi Pashine, Dong Wang, Jerry Zhang, Sree Kalyan Patiballa, Sven Witthaus, Mark D Shattuck, Corey S O'Hern, Rebecca Kramer-Bottiglio The mechanical properties of jammed granular materials are qualitatively different from continuum solids and their behavior is especially interesting close to the jamming transition. Most continuum solids have bulk (B) and shear (G) moduli that are within an order of magnitude of each other. In this work, we show that we can create granular metamaterials with bulk moduli that are up to three orders of magnitude larger than their shear moduli. To achieve this, we designed "particulated" granular metamaterials - flexible tessellations filled with a small number of solid particles in each cell. For under-constrained tessellated networks, the dominant contributions to B and G stem from particle-particle and particle-cell interactions. By filling the cells with specific particle configurations, we can tune the material's response, e.g. generating materials with G/B |
Wednesday, March 8, 2023 3:48PM - 4:00PM |
Q16.00005: Crimped fiber composites: Mechanics of a finite-length crimped fiber embedded in a soft matrix Nandan N Pitre, Sachin S Velankar Composites comprising crimped fibers of finite length embedded in a soft matrix have the potential to mimic the strain hardening behavior of tissues containing fibrous collagen. Unlike continuous fiber composites, such chopped fiber composites would be flow-processable. Here we study the fundamental mechanics of stress transfer between a single crimped fiber and the embedding matrix subjected to tensile strain. Finite element simulations show that fibers with large crimp amplitude and large relative modulus straighten significantly at small strain without bearing significant load. At large strain, they become taut and hence bear increasing load. Analogous to straight fiber composites, there is a region near the ends of each fiber which bears much lower stress than the mid-section. We show that the stress-transfer mechanics can be captured by a shear lag model where the crimped fiber can be replaced with an equivalent straight fiber whose effective modulus is lower than of the crimped fiber, but increases with applied strain. This allows estimating the modulus of a composite at low fiber fraction. The degree of strain hardening and the strain needed for strain hardening can be tuned by changing relative stiffness and crimp geometry. |
Wednesday, March 8, 2023 4:00PM - 4:12PM |
Q16.00006: A "mechanism-gradient" elasitic theory for planar kirigam Paul P Plucinsky, Ian Tobasco Recent reserach has shown that the soft modes of deformation in mechanism-based metamaterials, like origami and kirigami, are governed by an effective field theory (a PDE) linking the kinematics of their unit cell to the cell-averaged bulk deformation. Higher-order sources of elasticity dictate which solution to the effective theory will emerge under loads. Here we describe a "mechanism-gradient" theory that captures one-source of elasticity in planar kirigami (a model system for mechanism-based metamaterials). The theory is systematically derived from a general 2D hyperelasticity. A key ingredient to the derivation is the classical Flamant solution to isotropic linear elasticity, as it accounts for the "streching-like" distortion of the panels and hinges of soft modes in these system. |
Wednesday, March 8, 2023 4:12PM - 4:24PM |
Q16.00007: A generalized continuum elasticity theory for mechanical metamaterials Sourav Roy, Michael Wang, Gregory M Grason, Christian Santangelo Mechanical metamaterials have been studied extensively to explore the unusual mechanical properties owing to instabilities arising from their microstructures, yet challenges still remain in studying their complex deformations. We explore a simple continuum framework for the mechanics of a thin, metamaterial sheet in which a scalar field, coupled to the reference metric, captures the soft in-plane deformation of the material. In the Föppl–von Kármán limit, we show how the unusual elasticity of the sheet screens curvature-induced stress in the bulk for metamaterials with soft conformal and soft simple shear modes. We further use this framework to study the buckling of geometrically-frustrated metamaterial sheets. |
Wednesday, March 8, 2023 4:24PM - 4:36PM |
Q16.00008: Signatures of emerging order in complex structures via local structural analysis Maya Martirossyan, Matthew Spellings, Hillary Pan, Julia Dshemuchadse The emergence of crystalline order in assemblies with complex structures, such as Frank–Kasper phases and clathrates, is poorly described by existing theories of particle-by-particle attachment of a fluid to a crystal bulk. Molecular dynamics simulations of self-assembling, idealized particles performed using multi-well, isotropic pair potentials, allow us to explore this question more comprehensively by simulating the growth of structures with varying complexities and coordination numbers [1]. We study this fluid-to-crystal phase transition using two complementary techniques: coordination number analysis coupled with a machine-learning based order parameter [2] that uses spherical harmonics to describe and classify particles by their local environment, and can distinguish crystalline sites of the same coordination number by their differing local geometries. By tracking the how identical particles transition from their less well-defined liquid environment to their distinct “role” (Wyckoff position) within the bulk crystal, we study how the evolution of a particle’s local structure gives way to global crystalline order, which in turn enables us to extract general growth principles across structure types. These insights can guide in the design and assembly of materials with desired structures and functionalities in soft matter systems. |
Wednesday, March 8, 2023 4:36PM - 4:48PM |
Q16.00009: Structure and dynamics simulations of magnetically responsive particle-stabilized emulsion gels Ulf D Schiller, Nikhil Karthikeyan, Erin E O'Neill, James P Andrews Complex multicomponent fluids that undergo liquid-liquid phase separation have attracted interest as model systems for fluid-templated assembly of mesostructured soft materials. The interplay of phase behavior, fluid dynamics, and interfacial thermodynamics in these systems gives rise to interesting structure-property relations such as interfacial assembly and kinetically arrested phase morphologies. One particular example of kinetically arrested liquid mixtures are interfacially jammed emulsion gels (bijels) that emerge due to colloidal jamming during spinodal decomposition, resulting in an out-of-equilibrium liquid morphology with gel-like properties. Computational modeling and simulations can help gain a fundamental understanding of the structure and dynamics of particle-stabilized emulsions. We present lattice Boltzmann simulations of emulsion gels stabilized by anistropic particles. Magnetic particles facilitate controlled deformation and coalescence of particle-stabilized droplets and bijels by applied fields. The simulations shed light on the effect of magnetic fields on the domain size and morphology of liquid mesophases. The control mechanisms pave the way to engineered fluid templates with tailored structure, which can be leveraged to fabricate porous materials for filtration and separation. |
Wednesday, March 8, 2023 4:48PM - 5:00PM |
Q16.00010: Fast Hyperuniform Structure Generation with Tunable k-space Features Aaron H Shih, Mathias Casiulis, Stefano Martiniani Hyperuniform materials, characterized by the suppression of density fluctuations at large length scales or, equivalently, a structure factor decaying to zero at low wavevectors, are of great interest in the study of functional (e.g., optical bandgap) materials. We introduce a quasilinear-time structural optimization algorithm capable of generating large (N > 200,000) two- and three-dimensional hyperuniform structures significantly faster than previous approaches. Our method allows for high control of the structure factor in k-space and can jointly minimize other loss functions, such as pairwise repulsive interactions to generate sphere packings with desired spectral characteristics. As a result, we can inversely designmaterial structures exhibiting a variety of k-space features including anisotropy, n-fold symmetry, and disordered hyperuniformity, including stealthiness on specific length scales. Thus, systems approaching experimentally verifiable sizes can now be generated, and the relationship between 2-body statistics and emergent physical properties can be studied systematically at scale. |
Wednesday, March 8, 2023 5:00PM - 5:12PM |
Q16.00011: Modulating thermocapillary flow using light for logic operation at the air-water interface Nabila Tanjeem, Kendra Kreienbrink, Hyunki Kim, Ryan C Hayward
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Wednesday, March 8, 2023 5:12PM - 5:24PM |
Q16.00012: Design and Fabrication of Disordered Macroporous Photonic Materials Audrey von Raesfeld, Jennifer A McGuire, Anna B Stephenson, Vinothan N Manoharan Disordered photonic materials have unique wavelength-dependent optical properties such as near-isotropic structural coloration. Most previous studies of such materials have concerned direct photonic glasses, randomly packed spheres with a higher refractive index than the matrix they are embedded in (for example, polystyrene spheres in air). Direct photonic glasses are easy to make, but they can be fragile, and they offer limited control over optical properties. Both problems are overcome in inverse photonic glasses, in which a continuous matrix surrounds randomly packed, quasi-monodisperse low-refractive-index pores. Studies of inverse photonic glasses, however, are limited by a lack of easy fabrication methods. I will discuss the use of soft-materials fabrication methods such as emulsion and colloidal templating to make inverse photonic glasses with a wide range of matrix chemistries. Our approach is informed by Monte Carlo models of light transport that predict the optical properties of photonic glasses. I will also discuss how colloid and emulsion physics can be used to tailor the degree of disorder in these systems and manipulate their optical properties. |
Wednesday, March 8, 2023 5:24PM - 5:36PM |
Q16.00013: Colloidal Two-Dimensional Quantum Shells Mikhail Zamkov The development of spherically-layered semiconductor nanoparticles (colloidal quantum wells) is a promising innovation for the future of laser diodes. Traditional devices demonstrate a sharp decline in optical output of semiconductor nanoparticles as lasing power increases, negatively affecting the longevity and efficiency of the device. Colloidal quantum wells address this issue by optimizing the redistribution of incident power, preventing both energy loss and thermal damage. Investigating how to interface colloidal quantum wells with electrodes and how to ensure an efficient light propagation in the laser assembly is paramount to the project. A successful demonstration of laser diodes utilizing these particles will allow for photonic circuits to be produced at lower costs and provide a broad range of accessible colors by tuning the wavelength of emission. These properties allow for high compatibility with a wide variety of substrates and could lead to further breakthroughs in the fields of medical imaging, optical communications, and flexible substrate photonics. |
Wednesday, March 8, 2023 5:36PM - 5:48PM |
Q16.00014: Scattering cancellation and radiation torque and forces via spinning media Mohamed Farhat, Sebastien Guenneau, Ying Wu When pressure acoustic waves interact with rotating scatterers, they undergo peculiar and intriguing characteristics. In this talk, we will discuss our recent findings on physics of acoustic propagation in spinning fluids. We will start with a brief review on the mathematical modeling of the scattering via spinning object using the Mie scattering theory. Then we will showcase two examples. In one example, we develop a generalized scattering cancellation theory (SCT) to cloak the spinning objects and hide them from static observers. This work extends the realm of SCT and brings it one step closer to its practical realization that involves moving objects. In another example, we study the torque and force a spinning object experiences in evanescent acoustic fields, and show that the resulting discontinuity can scatter sound in unusual ways, e.g., a negative radiation force, although it has no imaginary part (associated to intrinsic absorption) in its parameters. |
Wednesday, March 8, 2023 5:48PM - 6:00PM |
Q16.00015: Acoustic spinning fibers: A new avenue towards airborne nonreciprocal waveguiding Mohamed Farhat, Pai-Yen Chen, Ying Wu Metamaterials with time-varying or moving components represent a paradigm shift in the way the interaction between acoustic (or optical) waves and material is thought of. In particular, spinning meta-atoms or scatterers may result in intriguing applications such as the intrinsic torque, negative radiation force (acoustic tweezers) [M. Farhat, et al. PRB(L) 104, L060104 (2021); M. Farhat, et al. APL In Press (2022)], or even novel invisibility cloaking devices [M. Farhat, et al. PRB 101, 174111 (2020)]. Interestingly, airborne acoustic waveguides and particularly the acoustic fiber still remain a challenging goal due to the lack of materials with speed of sound lower than air. In this talk, we report a radically novel approach for acoustic waveguiding, which relies solely on spinning air, i.e., without material modulation. Our proposal results in the acoustic analogue of optical fibers, that we coin here acoustic spinning fiber (ASF). Our findings show that this ASF is not only tunable, but also unidirectional [M. Farhat, et al. PRL Submitted (2022)], as spinning here acts as the counterpart of Zeeman effect. This may lead to several applications in acoustic metamaterials and sound-based communication. |
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